CARBONICOLA SUBCONSTRICTA. 59 



Dimensions : 



Antero-posteriorly . . . .48 mm. 



Dorso-ventrally . . . .27 mm. 



Laterally . . . . .15 mm. 



Locality. — Coal-shale, Polmont, near Falkirk. Springhill Colliery, near Kil- 

 marnock. Kirkwood Upper Coal-measures, Ell- coal, Kilwinning, Ayrshire. 



Observations. — I have met with this form only in Scotch localities. Unfortu- 

 nately I have not seen any testiferous examples, and am quite unable to state 

 anything as to the external characters of the shell. The form was originally 

 figured by Dr. Rhind in his little work ' The Age of the Earth,' and was named 

 Polmontensis by Captain Brown from the locality whence it was first obtained, and 

 he refigured the shell, giving a typical figure of the umbones and upper surface of 

 the shell as shown in a cast. In casts the peculiar long, narrow, widely-separated 

 umbones are quite characteristic. 



I figure specimens from the several Scotch localities, which are all in the 

 Upper Coal-measures. The figures show a slight variation in shape. 



The shell appears to have some resemblance to C. acuta, but it is flatter, and 

 differs from that species in the peculiarity of the umbones. 



6. Carbonicola subconstricta (Soiverby). Plate VI, fig. 44 ; Plate VII, figs. 5 — 15. 



Unio subconstbictus, Sow. Min. Conch., vol. i, 1812, p. 83, pi. xxxiii, figs. 1 — 3. 



— — Defiance. Diet. Sci. Nat., 1824, vol. xxxiii, p. 294. 



— — Dwmont. Constitution geologique Liege, 1832, p. 356. 



— — Ooldfuss. Petrefact. Germanise, 1834-40, pi. exxxi, fig. 18. 

 Cabdinia subconstbicta, Agassiz. Trad, de Sowerby's Min. Conch. (1842), p. 58, 



pi. xxiii, figs. 1 — 3. 

 — — de Koninck. Carb. Foss. de Belgique, 1842-4, p. 73, 



pi. I, fig. 9. 

 Pachyodon subteiangulabis, Brown. Ann. and Mag. Nat. Hist., 1843, vol. xii, 



p. 393, pi. xvi, fig. 6. 



— Smithii, Brown. Ibid., p. 393, pi. xvi, figs. 7, 8. 



— Embletoni, Brown. Ibid., p. 393, pi. xvi, fig. 9. 



— Hfiyn, Brown. Ibid., p. 393, pi. xvi, fig. 10. 



Unio subteiangulabis, Brown. Fossil Conch., 1849, p. 178, pi. Ixxiii, fig. 12. 



— Smithii, Brown. Ibid., p. 178, pi. Ixxiii, figs. 10, 11. 



— Embletoni, Brown. Ibid., p. 178, pi. Ixxiii, fig. 6. 



— Hetii, Brown. Ibid., p. 178, pi. Ixxiii, fig. 1. 



Caebonicola subconstbicta, M'Coy. Brit. Palaeozoic Foss., 1855, p. 515. 

 Antheacosia Smithii, King. Ann. Mag. Nat. Hist., ser. 2, vol. xvii, 1856, pi. iv, 



fig. 6. 



Specific Description. — Shell ovate ; anterior end rounded and short. Posterior 

 end obliquely truncate from above downwards and bluntly rounded. Somewhat 



